STUDIES ON CHARGE DISTRIBUTION ON THE SURFACE OF PROTEIN SHELL OF FERRITIN WITH A MASS SPECTROMETRIC TECHNOLOGY OF MATRIX-ASSISTED LASER DESORPTION IONIZATION/TIME OF FLIGHT(MALDI-TOF MS)
MALDI-TOF质谱技术研究铁蛋白蛋白壳表层的电荷分布

Liver ferritin of Dasyatis Akajei(DALF) was separated and purified with exclusion chromatography and DEAE-cellulose chromatography. After being purified, DALF was further separated by the grads of polyacrylantide gel electrophoresis to show two protein bands, a single molecular DALF and a dimmer ferritin. Using a technology of MALDI-TOF MS for studying the charge distribution, three peaks of molecular ion with different m/z from DALF were found on the surface of the ferritin, which are measured to be 10,369.41 m/z, 20,710.33 m/z and41,809.43 m/z. However, these peaks are disappearing while DALF was decomposed into the subunit, suggesting that there is positive charge area of high density on the surface of DALF protein shell. These phenomena are tightly connected to the electro-active properties of the protein. In order to understand the mechanism of picking up electrons from the physical electrode, a model was established to study the charge distribution on the surface of protein shell of DALF.